Cooling system, especially for electrical appliances

ABSTRACT

In order to cool an electrical appliance, a fuel storage tank ( 1 ) is provided, which has a connection ( 3 ) to a fuel cell ( 2 ) in order to feed fuel to it. Electrical consumers ( 4 ) are connected to the fuel cell ( 2 ). In their operating mode, the electrical consumers ( 4 ) represent heat sources ( 6 ). The electrical consumers are cooled by means of a thermally conductive connection ( 8 ) between heat sources ( 6 ) and a heat sink ( 7 ). The heat sink ( 7 ) results from the withdrawal of fuel from the fuel storage tank ( 1 ) for the operation of the fuel cell. The described cooling works without noise and is therefore particularly suitable for the use in PC systems.

[0001] The invention in question pertains to a cooling arrangement with electrical consumers that require cooling.

[0002] When electrical energy is transformed into other forms of energy, as well as when energy is transferred, losses occur. Losses also occur in all electrical consumers, such as electronic circuits. Waste heat is thus generated. This generation of waste heat is increasingly problematic, because of increasingly high integration density and pulse rates in electronic circuits. While just a few years ago, it was still possible to cool microprocessors of computer systems with passive components such as heat sinks or the natural convection of the air; today's processors in PC or notebook systems currently on the market require active, typically electrically driven ventilators in order to dissipate waste heat. Waste heat in power receptacles, storage components, and drives of computer systems also frequently needs to be dissipated with the help of additional components such as ventilators or so-called heat pipes.

[0003] The dissipation of waste heat in electronic systems is absolutely necessary in order to prevent an unacceptable increase in temperature in the components or elements in question, thus preventing the possible destruction as well as other resultant damage.

[0004] When active cooling elements such as ventilators are used, the resulting increase in total weight of the electrical system in question, as well as additional requirements regarding assembly, logistics and qualification of personnel pose a problem. Another problem lies in the possible failure of active components such as ventilators, which can cause expensive resultant damage. In addition to this, the operation of electrical ventilators causes unwanted background noise. These unwanted noises are especially inconvenient when ventilators are used in PC systems or notebooks, because at such work places the user requires an increased ability to concentrate.

[0005] In the magazine “c't Magazin für Computer Technik”, edition 11, 1998, page 41, published by Heise Verlag, Hannover, Germany, an article by Dr. Jürgen Rink, titled “Dauerläufer, Brennstoffzellen fir Notebooks” (“long-distance runners, fuel cells for notebooks”) mentions a notebook with a fuel cell for electrical power supply.

[0006] The task of the invention at hand is to present a cooling arrangement which cools without sound, in particular for electrical appliances.

[0007] With regards to the arrangement, this task is realized with a cooling arrangement, particularly for electrical appliances, which contains

[0008] a fuel cell,

[0009] at least one electrical consumer which is connected to the fuel cell by means of an electrically conductive connection, and which in its operating state is a heat source,

[0010] a fuel storage tank which is connected to the fuel cell for the purpose of feeding fuel to it, and which is a heat sink in its operating state (characterized by the withdrawal of fuel), and

[0011] a thermally conductive connection between heat source and heat sink.

[0012] The invention is based on the principle of withdrawing heat from, or cooling electrical consumers which generate waste heat, by creating a thermally well-conductive connection between the electrical consumer and a heat sink. A heat sink results from the removal of fuel from a fuel storage tank, for example by means of an expansion of the fuel or other thermodynamic processes which draw heat from their environment.

[0013] The described principle has the advantage that it cools without sound. This is particularly significant for the application of this principle in electrical systems that are used at office work places. In addition to this, the described principle can be realized easily and in a cost-effective manner.

[0014] Additionally, a fuel cell is provided, which is connected to the fuel storage tank in order to feed fuel to the fuel cell. The fuel cell is also electrically connected to at least one electrical consumer. A fuel cell is a galvanic cell, in which chemical energy is transformed into electrical energy. The process within the fuel cell is hereby referred to as cold fire. Fuel cells can be operated for example with hydrogen and oxygen. Since the oxygen can be taken from the surrounding air, only the hydrogen needs to be storable as fuel in a hydrogen storage tank. Moreover, the hydrogen can be stored in the form of liquefied gas, or it can be bound in a hydride storage tank. When hydrogen is taken from a hydride storage tank, heat is withdrawn from the environment. There thus exists a heat sink. The fuel taken from the tank is fed into a fuel cell, in which electrical energy is produced, whereas the amount of produced energy depends on the amount of fuel taken from the tank. Electrical consumers can be connected to the fuel cell. These electrical consumers can produce waste heat. This waste heat in the electrical consumers is thus linked to the withdrawal of hydrogen from the fuel storage tank. If the electrical consumers representing the heat source are thermally linked to the heat sink, the thus achieved cooling of the electrical consumers is advantageous, since the cooling effect is especially good when a lot of waste heat is incurred and, vice versa, the cooling effect is less when only a little waste heat is incurred.

[0015] If the electrical system is a portable computer system, the described cooling is particularly advantageous, since no additional electrical energy is required for the active coolers, such as ventilators, and since noisy cooling elements are especially inconvenient for the user during operation of portable computer systems.

[0016] Fuel cells that are used to produce electrical energy for portable computer systems, in connection with hydride storage tanks, allow for a long operating period independent from external power supply. With traditional batteries and accumulators, operation independent from an external power source is limited to a few hours. The described cooling arrangement can for instance be used in portable computers (notebooks, laptops) for energy supply and cooling, in order to combine the advantage of long periods of operation independent from external power supply with the cooling of high-performance components, such as processors.

[0017] The application of the described principle also makes sense in other electrically driven small appliances, especially in the field of information and communication technology, when the desire for long operating periods without recharging externally meets with the need for active cooling. Such applications could for instance be organizers, PDAs (Personal Digital Assistants), and mobile phones.

[0018] Moreover, the application of the described principle is conceivable in motor vehicles, which are electrically driven by means of a fuel cell, and which contain an electrical motor which produces heat during operation and requires cooling, and to that end is thermally connected with the fuel storage tank necessary for the operation of the fuel cell.

[0019] In another advantageous model of the invention in question, the fuel storage tank is a hydride storage tank. Hydrogen or another fuel suitable for the reaction within fuel cells is bound in hydride storage tanks, for example in the form of lithium hydride or metal hydrides.

[0020] In another advantageous model of the invention in question, at least one of the electrical consumers requiring cooling is the processor of a computer system. Central processing units (CPU) of computer systems show especially high integration density and pulse rates. Therefore, the power dissipation per area or per volume is especially high. The deflection of the waste heat is thus of great significance.

[0021] Other model variants of the invention in question are mentioned in the sub claims.

[0022] Below, the invention in question is explained further, based on one model, with reference to the drawings.

[0023] Showing as follows:

[0024] The FIGURE shows a block diagram of a principle-adhering model of the invention in question.

[0025] The FIGURE shows a fuel storage tank 1, which is connected to a fuel cell 2. Between the fuel storage tank 1 and the fuel cell 2, a connection 3 is provided. This connection 3 is made gastight, in order to feed for example gaseous hydrogen to the fuel cell 2. Electrical consumers 4 are connected to the fuel cell 2. In order to accommodate this, electrical lines 5 are arranged in-between the fuel cell 2 and the electrical consumers 4. In the operating mode, the fuel cell produces electrical energy, which is led to the electrical consumers 4 via the lines 5. These electrical consumers act as heat sources 6 during operation. The fuel storage tank 1, from which fuel is taken during operation, represents a heat sink 7, since heat is withdrawn from the surroundings, for instance through the expansion of the fuel. In order to cool the electrical consumers 4, thermally conductive connections 8 are arranged in-between the heat sources 6 and the heat sink 7. Heat is transported from the heat sources 6 to the heat sink 7 by means of the thermally conductive connections 8.

[0026] The described arrangement has the advantage that the electrical consumers can be cooled with a fuel storage tank, which, in connection with a fuel cell, is required anyway in order to supply power to the electrical system. Moreover, it is advantageous that the cooling effect is especially good when a particularly high amount of waste heat needs to be dissipated. This is the case when a lot of energy is produced in the fuel cell and thereby a lot of fuel is withdrawn from the fuel storage tank.

[0027] When the described cooling method is used in a portable computer system such as a notebook, which has a fuel cell in order to produce the necessary electrical energy, the otherwise indismissible noise-producing ventilators for active cooling of electrical components can be omitted.

[0028] In the model in question, the fuel storage tank 1 is filled with hydrogen, which reacts with oxygen in the fuel cell 2 in order to produce energy. However, an operation with other fuels, such as methanol, is also conceivable. The hydrogen is bound in a hydride storage tank in a reversible process. When hydrogen is taken from the hydride storage tank and hydrogen expands, a heat sink results. Since the hydride storage tank can be recharged, the described arrangement can be put to use in portable computer systems in an advantageous manner. 

1) cooling arrangement, in particular for elecrical appliances with one fuel cell (2), at least one electrical consumer (4), which is connected to the fuel cell (2) via an electrically conductive connection (5), and which in its operating mode is a heat source (6), a fuel storage tank (1), which is connected to the fuel cell (2) for the purpose of feeding fuel into it, and which in its operating state, characterized by the withdrawal of fuel, is a heat sink (7), and a thermally conductive connection (8) between heat source (6) and heat sink (7). 2) Cooling arrangement according to claim 1, characterized by the fact that the electrical appliance is a portable computer system. 3) Cooling arrangement according to claim 1 or 2, characterized by the fact that the fuel storage tank (1) is a hydride storage tank. 4) Cooling arrangement according to one of the claims 1 through 3, characterized by the fact that at least one electrical consumer (4) is a central processing unit in a computer system. 